CN104856691A - Retina blood oxygen saturation measurement method based on fundus cameras - Google Patents

Abstract

The invention relates to a retina blood oxygen saturation measurement method based on fundus cameras. Various shortcomings exist in an existing method. According to the method of the invention, refitting is carried out with an existing fundus camera as a platform, i.e., a 50:50 spectrometer is additionally installed so that fundus reflection light is averagely divided into two parts. Only the light with sensitive wavelength and the light with non-sensitive wavelength for oxyhemoglobin and deoxyhemoglobin are respectively allowed to pass through after being filtered and are respectively exposed to the two high-resolution digital cameras, so that two retina images under the same light source illumination intensity and the different wave length light conditions are obtained. Through analysis and data processing of the two retina digital images, light intensity values of retina nerve fiber layer image pixel points in an artery blood vessel, in a vein blood vessel and beside the blood vessels are obtained; and through analysis of the light intensity values in the blood vessel images, the proportion, namely the blood oxygen saturation, of the oxyhemoglobin in the retinal vessels is obtained. The retina blood oxygen saturation measurement method is easy to operate and does not bring wounds; and the retina artery blood oxygen saturation and the vein blood oxygen saturation can be obtained at the same time.

Description

A kind of method of the retinal blood oxygen saturation measurements based on fundus camera

Technical field

The present invention relates to a kind of method of oxygen saturation measurement, particularly for the method for the oxygen saturation measurement of blood in retina artery and vein vascular.

Background technology

Many ophthalmic diseasess and systemic disease, as glaucoma, retinitis pigmentosa, senile degeneration of macula, hypertension, diabetes, multiple sclerosis etc., all hypoxic-ischemics of the eye ground tissue of various degrees.Along with increasing the weight of of the state of an illness, there will be the atrophy of cerebral stratum of retina, the oozing out of retinal tissue, edema and the pathological manifestations such as hemorrhage and have a strong impact on vision.If clinically can the blood oxygen saturation of early monitoring retinal tissue and blood oxygen availability, there is important help by the early diagnosis and therapy of these diseases.

The method measuring blood oxygen saturation at present clinically has chemical method and optical method two kinds.Chemical method utilizes oxysensible anodic-cathodic, in the solution environmental of aerobic, redox reaction occurs and the principle of generation current, thus measure the partial pressure of oxygen in this solution.The blood gas analyzer of clinical middle use is exactly utilize optical method principle directly to measure partial pressure of oxygen in blood.The method accuracy is higher, but needs to extract human body large artery trunks blood (as femoral artery), be a kind of inspection method having wound, and measurement result is subject to the store method of blood preparation and the impact of holding time.Optical method is blood oxygen saturation in indirect analysis blood according to the oxygenate principle different with the absorbing amount of deoxyhemoglobin to different wave length light.The Fingerstall-type blood oxygen measuring apparatus used clinically utilizes this principle exactly.It is usually used in the blood oxygen saturation of the distal aorta measuring the positions such as human finger, ear-lobe, toe.It is a kind of noinvasive, can Real-Time Monitoring and method easy to use.But be subject to the light transmission impact detecting the tissues such as area skin.

Above two kinds of conventional clinically blood oxygen measuring methods reflections be blood oxygen concentration in human body trunk blood or tip circulating blood, not we wish the blood oxygen saturation of the destination organization of direct-detection, more cannot understand the actual blood oxygen Utilization ability of this destination organization.

Retinal vessel is the blood vessel that uniquely can directly be visually noticeable in human body.By ophthalmofundoscope or fundus camera, arteria retina and retinal vein all can directly be irradiated by light and observed.Therefore, eye ground tissue will be the ideal tissue carrying out arteriovenous blood oxygen concentration and the research of blood oxygen availability.

Existing commercial fundus camera can obtain Radix Rumicis, gem-pure eye ground blood-vessel image.The commercial fundus camera of part also has the optics side hole can carrying out Function Extension, is very beneficial for carrying out retinal vessel blood oxygen analysis measurement after we reequip.

Summary of the invention

The object of this invention is to provide a kind of method of the retinal blood oxygen saturation measurements based on fundus camera, the method can realize by carrying out simple refit to existing fundus photography machine equipment.

The required device of the inventive method comprises:

1, with the commercial fundus camera in side hole, described fundus camera carries flash of light and comprises the visible ray of wavelength in 380nm ~ 780nm scope;

2,50: 50 spectrometers;

3, two cover filtering apparatus, described filtering apparatus is filter glass, by the light of specific wavelength;

4, two cover image collecting devices, described image collector is set to the high-resolution digital camera that pixel is greater than 2,000 ten thousand;

5, data analysis set-up, described data analysis set-up is for carrying out image analysis computer.

The step of the method for concrete measurement retinal blood oxygen saturation is as follows:

Step 1: the fundus camera applied with side hole carries out optical fundus to testee and takes pictures;

Step 2: the light come by fundus reflex is divided into two-way by 50: 50 spectrometers be arranged in the light path of fundus camera side hole;

Step 3: the two-way light after light splitting after being arranged on the filtering apparatus in light splitting optical path, respectively by means of only the light to HbO2 Oxyhemoglobin and deoxyhemoglobin sensitive wave length and insensitive wavelength;

Described is 440nm, 600nm, 605nm or 660nm to the wavelength of HbO2 Oxyhemoglobin and the responsive light of deoxyhemoglobin, and HbO2 Oxyhemoglobin and deoxyhemoglobin have visibly different absorbance to this sensitive wave length light;

Described is 506nm, 548nm, 569nm or 586nm to the wavelength of HbO2 Oxyhemoglobin and the insensitive light of deoxyhemoglobin, and HbO2 Oxyhemoglobin is almost identical with the absorbance of deoxyhemoglobin to this wavelength light;

Step 4: the Single wavelength eye fundus image of described responsive light and insensitive light is exposed to two described cover image collecting devices respectively, obtains the optical fundus digital image under two Compound eyes;

Step 5: by the optical fundus digital image input data analysis device under two Compound eyes, obtains the pixel light intensity level of optional position in image; Data analysis set-up adopts image analysis program namely can realize the pixel light intensity level of optional position in image, and this technology is ripe prior art;

In eye fundus image, the individual point of n (n=5 ~ 15) is chosen respectively with this retinal vessel side in the retinal vessel of Water demand, obtain the pixel light intensity level I in this retinal vessel, and the pixel light average strength I of the other each point of this retinal vessel ₀, the optical density OD (Optical densities) of this retinal vessel can be obtained with following formula:

$\mathrm{OD}=\log \left(\frac{I_0}{I}\right)---\left(1\right)$

Adopt said method, in the Single wavelength eye fundus image of responsive light and insensitive light, draw the optical density in same vessel district respectively, i.e. OD _{sensitive wave length}and OD _{non-sensitive wavelength}, obtain Reinhoit Zahl ODR (Optical density ratios) by following formula:

According to Lambert-Beer law, Reinhoit Zahl and blood oxygen saturation SO ₂there is linear correlation, then blood oxygen saturation SO ₂for:

SO ₂＝a+b×ODR (3)

A and b in formula (3) is constant, can be obtained by the photodensitometry of the blood vessel to known blood oxygen saturation.

By the existing fundus photography machine equipment of repacking in the present invention, spectroscope is installed, by the optical filter of specific wavelength, obtains the fundus photograph under hemoglobin sensitive wave length light and non-sensitive wavelength light are irradiated respectively.Clearance related software is analyzed image, can obtain optical density (Optical densities OD) and the Reinhoit Zahl (Opticaldensity ratios ODR) in fundus photograph arterial blood area under control and venous blood area under control.According to Lambert-Beer law, Reinhoit Zahl (ODR) and HbO2 Oxyhemoglobin percentage ratio, namely there is linear correlation principle in blood oxygen saturation (SO2), and we can obtain the blood oxygen saturation in different blood vessel district.This method directly analyzes the reflected light of arteria retina and venous blood, overcomes other optical methods and be subject to when measuring peripheral circulation blood oxygen saturation detect position, as finger, and the skin effects at the places such as ear-lobe; Meanwhile, this method can measure the keeping blood vessel-arteria retina of retinal tissue and the blood oxygen saturation of backflow blood vessel-retinal vein simultaneously, therefore, can obtain the actual blood oxygen availability of retinal tissue according to arteriovenous blood oxygen saturation difference.

This method noinvasive, simple and practical.By the simple refit to existing fundus camera, without the need to adding the light supply apparatus producing specific wavelength in addition, greatly saving equipment cost, also extending the application function of existing fundus photography machine equipment.

Accompanying drawing explanation

Fig. 1 is the structural representation that the inventive method adopts device;

Fig. 2 is the inventive method examples measure workflow diagram.

Detailed description of the invention

As shown in Figure 1, the eye ground oxygen saturation measurement device based on fundus camera comprises:

1, commercial fundus camera 1, described fundus camera, with side hole 2, carries flash of light and comprises the visible ray of wavelength in 380nm ~ 780nm scope, as Topcon series fundus camera;

2,50: 50 light splitting, 3;

3, two cover filtering apparatus 3 and 4, described filtering apparatus is filter glass, by the light of specific wavelength;

4, two cover image collecting devices 6 and 7, described image collector is set to the high-resolution digital camera that pixel is greater than 2,000 ten thousand;

5, data analysis set-up 8, described data analysis set-up is for carrying out image analysis computer.

As shown in Figure 2, the step of the method for concrete measurement retinal blood oxygen saturation is as follows:

Step 1: the fundus camera applied with side hole carries out optical fundus to testee and takes pictures;

Step 2: the light come by fundus reflex is divided into two-way by 50: 50 spectrometers be arranged in the light path of fundus camera side hole;

Step 3: the two-way light after light splitting after being arranged on the filtering apparatus in light splitting optical path, respectively by means of only the light to HbO2 Oxyhemoglobin and deoxyhemoglobin sensitive wave length and insensitive wavelength;

Described is 440nm, 600nm, 605nm or 660nm to the wavelength of HbO2 Oxyhemoglobin and the responsive light of deoxyhemoglobin, and HbO2 Oxyhemoglobin and deoxyhemoglobin have visibly different absorbance to this sensitive wave length light; The present embodiment adopts wavelength to be 605nm;

Described is 506nm, 548nm, 569nm or 586nm to the wavelength of HbO2 Oxyhemoglobin and the insensitive light of deoxyhemoglobin, and HbO2 Oxyhemoglobin is almost identical with the absorbance of deoxyhemoglobin to this wavelength light; The present embodiment adopts wavelength to be 586nm;

Step 4: the Single wavelength eye fundus image of described responsive light and insensitive light is exposed to two described cover image collecting devices respectively, obtains the optical fundus digital image under two Compound eyes;

Step 5: by the optical fundus digital image input data analysis device under two Compound eyes, obtains the pixel light intensity level of optional position in image; Data analysis set-up adopts image analysis program namely can realize the pixel light intensity level of optional position in image, and this technology is ripe prior art;

In eye fundus image, the individual point of n (n=5 ~ 15) is chosen respectively with this retinal vessel side in the retinal vessel of Water demand, obtain the pixel light intensity level I in this retinal vessel, and the pixel light average strength I of the other each point of this retinal vessel ₀, the optical density OD (Optical densities) of this retinal vessel can be obtained with following formula:

$\mathrm{OD}=\log \left(\frac{I_0}{I}\right)---\left(1\right)$

Adopt said method, in the Single wavelength eye fundus image of responsive light and insensitive light, draw the optical density in same vessel district respectively, i.e. OD _{sensitive wave length}and OD _{non-sensitive wavelength}, obtain Reinhoit Zahl ODR (Optical density ratios) by following formula:

According to Lambert-Beer law, Reinhoit Zahl and blood oxygen saturation SO ₂there is linear correlation, then blood oxygen saturation SO ₂for:

SO ₂＝a+b×ODR (3)

A and b in formula (3) is constant, can be obtained by the photodensitometry of the blood vessel to known blood oxygen saturation.

Claims (2)

1., based on a method for the retinal blood oxygen saturation measurements of fundus camera, it is characterized in that the device needed for the method comprises:

(1) with the commercial fundus camera in side hole, described fundus camera carries flash of light and comprises the visible ray of wavelength in 380nm ~ 780nm scope;

(2) 50: 50 spectrometers;

(3) two cover filtering apparatus, described filtering apparatus is filter glass, by the light of specific wavelength;

(4) two cover image collecting devices, described image collector is set to the high-resolution digital camera that pixel is greater than 2,000 ten thousand;

(5) data analysis set-up, described data analysis set-up is for can carry out image analysis computer;

The step of the method for concrete measurement retinal blood oxygen saturation is as follows:

Step 1: the fundus camera applied with side hole carries out optical fundus to testee and takes pictures;

Step 2: the light come by fundus reflex is divided into two-way by 50: 50 spectrometers be arranged in the light path of fundus camera side hole;

Step 3: the two-way light after light splitting after being arranged on the filtering apparatus in light splitting optical path, respectively by means of only the light to HbO2 Oxyhemoglobin and deoxyhemoglobin sensitive wave length and insensitive wavelength;

Step 4: the Single wavelength eye fundus image of described responsive light and insensitive light is exposed to two described cover image collecting devices respectively, obtains the optical fundus digital image under two Compound eyes;

Step 5: by the optical fundus digital image input data analysis device under two Compound eyes, data analysis set-up, by graphical analysis, obtains the pixel light intensity level of optional position in image;

In eye fundus image, in the retinal vessel of Water demand, choose n point respectively, n=5 ~ 15 with this retinal vessel side, obtain the pixel light intensity level I in this retinal vessel, and the pixel light average strength I of the other each point of this retinal vessel ₀, the optical density OD of this retinal vessel can be obtained with following formula:

$\mathrm{OD}=\log \left(\frac{I_0}{I}\right)---\left(1\right)$

Adopt said method, in the Single wavelength eye fundus image of responsive light and insensitive light, draw the optical density in same vessel district respectively, i.e. OD _{sensitive wave length}and OD _{non-sensitive wavelength}, obtain Reinhoit Zahl ODR by following formula:

According to Lambert-Beer law, Reinhoit Zahl and blood oxygen saturation SO ₂there is linear correlation, then blood oxygen saturation SO ₂for:

SO ₂＝a+b×ODR (3)

A and b in formula (3) is constant, can be obtained by the photodensitometry of the blood vessel to known blood oxygen saturation.

2. the method for a kind of retinal blood oxygen saturation measurements based on fundus camera as claimed in claim 1, is characterized in that:

Described is 440nm, 600nm, 605nm or 660nm to the wavelength of HbO2 Oxyhemoglobin and the responsive light of deoxyhemoglobin, and HbO2 Oxyhemoglobin and deoxyhemoglobin have visibly different absorbance to this sensitive wave length light;

Described is 506nm, 548nm, 569nm or 586nm to the wavelength of HbO2 Oxyhemoglobin and the insensitive light of deoxyhemoglobin, and HbO2 Oxyhemoglobin is almost identical with the absorbance of deoxyhemoglobin to this wavelength light.